Use of single-stage low protein diets for growing Leghorn pullets.
Two experiments were conducted in which growing White Leghorn pullets were fed single-stage 14% CP diets from 0 to 19 weeks. In the first trial, diet treatments were 1) conventional step-down protein, 2) reverse-protein, 3) 14% CP single-stage with methionine and lysine adjusted to 2 and 5% of CP, respectively, 4) as per 3 to 12 weeks followed by 14% CP with no amino acid constraints to 19 weeks. Each treatment was tested with 14 replicated cages each of 11 commercial strain Leghorn pullets. Single-stage 14% CP diets reduced pullet weight to 16 weeks relative to conventionalLy fed birds, although after this time no significant (P greater than .05) effect was observed. Pullets fed the reverse-protein diets were significantly (P less than .01) smaller than birds from all other treatments. During a subsequent 52-week laying period, rearing treatment had no significant effect on egg production, egg weight, shell deformation, feed intake, or Haugh units. A second trial was conducted to note the effect of energy level on the birds' response to low-protein diets. Diets of 14.4% CP were formulated to provide either 2610 or 3164-kcal ME/kg. A third treatment allowed for self-selection of two diets providing concentrated sources fo protein or energy. Each treatment was tested with nine replicate cages of 10 commercial strain White Leghorn pullets. Dietary energy had little effect on pullet development. Although birds offered the low-energy diets consistently consumed more protein, diet had no effect on body weight or carcass composition at 18 weeks. The data indicate that single-stage low-protein diets are suitable for growing pullets to maturity. Compared to a conventional step-down protein program, the single-stage 14% CP diet does not control body weight but does give comparable laying performance, albeit at reduced protein intake during rearing. The simplicity of the program is discussed relative to industry needs.